Field of the Invention
The present invention relates to technology of testing input/output interfaces which comply with USB 3.0 standard and, more particularly, to a universal serial bus (USB) testing method and a testing fixture board for a USB device.
Description of the Prior Art
Universal serial bus (USB) interface is the input/output interface most widely used. A USB device, such as a mouse, keyboard, printer, hard disk drive, USB flash drive, camera, cellular phone, tablet, laptop, personal computer, set-top box, or game console, can be linked to another USB device by the USB interface in order to exchange data.
To test and determine whether USB interfaces of USB devices function well, USB device delivery inspection requires a testing worker to conduct a quality test on the USB interfaces. Regarding the physical layer testing specifications of USB 2.0, USB Implementers Forum (USB IF) sets forth three testing specifications for low speed, full speed, and high speed, respectively. The USB High-Speed Electrical Test Tool provided by the USB IF controls how a USB device under test sends specific testing packets when operated by a conventional operating system, and the testing packets are observed with an oscilloscope to confirm the compatibility and signal quality of the USB interface of the USB device which meets USB 2.0 standard.
Unlike USB 2.0 standard, USB 3.0 standard features greatly simplified testing specifications and testing techniques. USB 3.0 interface chips of USB devices operated by a conventional operating system are preconfigured with a test mode. In the situation where connecting a USB device under test to a testing fixture board is not followed by any response for a while, a USB interface chip mounted on the USB device under test enters a compatibility mode directly. In the compatibility mode, the USB device under test starts sending testing packets so that an oscilloscope measures the testing packets through the testing fixture board and displays the measured testing packets, allowing a testing worker to confirm and support the compatibility and signal quality of the USB interface of the USB device under test.
However, testing techniques applicable to USB 3.0 interfaces are useless to a USB device with a USB 3.0 interface, if the USB device is an embedded system.